X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from EXHUB003-4.exch003intermedia.net ([207.5.74.111] verified) by logan.com (CommuniGate Pro SMTP 5.3.5) with ESMTPS id 4222548 for flyrotary@lancaironline.net; Thu, 15 Apr 2010 11:12:54 -0400 Received-SPF: none receiver=logan.com; client-ip=207.5.74.111; envelope-from=jwhaley@datacast.com Received: from EXVMBX003-5.exch003intermedia.net ([207.5.74.45]) by EXHUB003-4.exch003intermedia.net ([207.5.74.111]) with mapi; Thu, 15 Apr 2010 08:12:17 -0700 From: Jeff Whaley To: 'Rotary motors in aircraft' Date: Thu, 15 Apr 2010 08:13:10 -0700 Subject: Weird sound during descent Thread-Topic: Weird sound during descent Thread-Index: AcrcrikxOXI2YlsxS36UT5oQuqE0VA== Message-ID: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US Content-Type: multipart/alternative; boundary="_000_C03ABB0A7362B84BB53D544B3C305E0E017944B45AE2EXVMBX0035e_" MIME-Version: 1.0 --_000_C03ABB0A7362B84BB53D544B3C305E0E017944B45AE2EXVMBX0035e_ Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable I have been hearing a weird buzzing sound usually detectable on base leg at= low power settings. It is hard to describe in text but is repeatedly as z= zuuzz, zzuuzz, zzuuzz . I thought it was wind noise escaping between the fuselage and gear legs, as= there are no fairings between the fuselage and top of the cub-style gear. Last night it was bit bumpy and during one descent there was a good bump th= at lifted me against the seat belts -- the noise stopped. Tracy had cautioned me against low power steeps descents, something about t= hrust bearing and/or snubber - maybe refresh me on that one Tracy? However, an approach speed of 500 fpm, 80 mph, 3000 rpm, mp <10", is not wh= at I'd consider steep. Anyone care to give me a clue as to what I might be hearing? If I get a chance to fly this weekend, I'll experiment to see if I can stop= /change the noise with speed or attitude adjustments. Jeff __________ Information from ESET NOD32 Antivirus, version of virus signatur= e database 5031 (20100415) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com This message, and the documents attached hereto, is intended only for the a= ddressee and may contain privileged or confidential information. Any unauth= orized disclosure is strictly prohibited. If you have received this message= in error, please notify us immediately so that we may correct our internal= records. Please then delete the original message. Thank you. --_000_C03ABB0A7362B84BB53D544B3C305E0E017944B45AE2EXVMBX0035e_ Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

I have been hearing a weird buzzing sound usually de= tectable on base leg at low power settings. It is hard to describe in= text but is repeatedly as zzuuzz, zzuuzz, zzuuzz .

I thought it was wind noise escaping between the fus= elage and gear legs, as there are no fairings between the fuselage and top = of the cub-style gear.

Last night it was bit bumpy and during one descent t= here was a good bump that lifted me against the seat belts -- the noise sto= pped.

Tracy had cautioned me against low power steeps desc= ents, something about thrust bearing and/or snubber – maybe refresh m= e on that one Tracy?

However, an approach speed of 500 fpm, 80 mph, 3000 = rpm, mp <10”, is not what I’d consider steep.

Anyone care to give me a clue as to what I might be = hearing?

If I get a chance to fly this weekend, I’ll ex= periment to see if I can stop/change the noise with speed or attitude adjus= tments.

Jeff

__________ Information from ESET NOD32 Antivirus, version of virus signatur= e database 5031 (20100415) __________

The message was checked by ESET NOD32 Antivirus.

http://www.eset.com

This message, and the docum= ents attached hereto, is intended only for the addressee and may contain pr= ivileged or confidential information. Any unauthorized disclosure is strict= ly prohibited. If you have received this message in error, please notify us immediately so that we may correct our = internal records. Please then delete the original message. Thank you.
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